Field of the Invention
The present invention relates to a method and system for the provision of communication session control in a local area network.
Description of the Related Art
The increasing deployment of broadband Internet access to the homes through network technologies such as the digital subscriber line (DSL) has created an opportunity to support new communication experiences by making the home an increasingly important networking center.
Digital content is becoming the predominant format for storing, viewing and managing media. Consumers want to enjoy content across different consumer electronic (CE) appliances and from many locations in their homes. Also personal communication is converging towards the digital streaming format, and the definition of a common set of technology standards to ensure interoperability between content and communication devices is a compelling requirement. For example, the Digital Living Network Alliance (DLNA) has issued a set of interoperability guidelines that define a framework of interoperable components for devices and services. The guidelines recommend the adoption of consolidated Internet standards, such as Internet Protocol (IP), Hyper Text Transfer Protocol (HTTP) and UPnP technology.
As well known in the art, according to proposed standard RFC3261 and extension thereof, Session Initiation Protocol (SIP) is an application-layer control and signalling protocol developed by the Internet Engineering Task Force (“IETF”) for creating, modifying and terminating interactive communication sessions between one or more participants. These sessions may include Internet telephone calls, multimedia distribution, and multimedia sessions such as voice and/or video conference, supporting user mobility, negotiation of multimedia end-point capabilities through the integration with a Session Description Protocol (SDP), call routing and session transfer functionalities.
SIP was accepted by the Third Generation Partnership Project (3GPP) as signaling protocol of the IP Multimedia Subsystem (IMS) architecture. Indeed, it is widely assumed that SIP-based communications will gradually replace traditional Public Switched Telephone Network (PSTN), due to lower management costs and higher flexibility in the combination of different media, such as audio, video, and text.
On the other hand, Universal Plug and Play (UPnP) technology establishes protocols that allow consumer electronic (CE) appliances in a local area network to interact with each other.
UPnP architecture establishes a set of standardized protocols that consumer electronic (CE) appliances implement to provide discovery, control and data transfer between such appliances. Examples of appliances that may be configured to implement UPnP protocols include computers, servers, printers, telephones, digital cameras, video recorders, Internet personal appliances, or personal digital assistants. UPnP architecture distinguishes between UPnP devices which expose services and UPnP control points which discover and use such services.
Accordingly, the UPnP architecture provides for a typical client/server model that distinguishes between service providers (devices) and service consumers (control-points). For example, a UPnP TV device may provide a service for viewing digital media, whilst the TV's remote control may act as control-point of the TV.
UPnP employs a protocol named Simple Service Discovery Protocol (SSDP) to discover available devices on the local, network and a protocol named Simple Object Access Protocol (SOAP) as mechanism to invoke service operations provided by devices. SSDP uses a multicast variant of HTTP (HTTPMU) that exploits the IP multicast service available on the local area network. HTTPMU is used by UPnP devices to send advertisement messages and by control points to send search requests for finding available UPnP services.
Besides, UPnP also defines a mechanism to manage event notifications related to changes in the state of a UPnP device, based on the General Event Notification Architecture (GENA) as defined by the IETF in two Internet drafts (“General Event Notification Architecture Base”, J. Cohen, S. Aggarwal, 9 Jul. 1998, <draft-cohen-gena-p-base-01.txt>; and “General Event Notification Architecture Base: Client to Arbiter”, J. Cohen, S. Aggarwal, Y. Y. Goland, 6 Sep. 2000, <draft-cohen-gena-p-base-01.txt>). This mechanism is based on a subscription that a control-point can make to receive notifications about changes in state variables associated with a UPnP device.
Due to the nature of UPnP service discovery and eventing mechanism, UPnP technology is limited to network devices that are connected in a network environment where multicasting is supported.
Hitherto, the main effort of the UPnP standardization process for multimedia devices has been focused on content-based services. The UPnP AV Architecture document and the MediaServer and MediaRenderer standard device specifications are the result of this activity. This standard explicitly states that enabling two-way interactive communication services (such as audio and video conferencing) is outside the goal of the UPnP AV Architecture, albeit some proposals in that direction have recently been submitted.
US-2006/0140199-A1 and US-2006/0153072-A1 disclose an architecture and mechanism for bridging the UPnP and SIP protocols. The documents describe a proxy apparatus for translating UPnP messages into SIP messages. The proxy parses the structured XML content of a UPnP SOAP invocation and embeds said XML in the header part, body part, or both of the corresponding SIP message. Although such approach is very general, the syntactic translation of messages enables the mere transportation of UPnP messages using SIP requests/responses as carrier protocol, whereby a SIP device (e.g. a mobile phone) can be employed for controlling UPnP devices/services. The Applicant notes that these documents teach to use the SIP protocol as a means to access UPnP services and devices from outside the home network environment exploiting location and routing services offered by SIP-enabled networks, but does not specifically address the issue of controlling a conference session trough the UPnP protocol. Moreover, the disclosed approach accounts for syntactic translations between UPnP and SIP protocols, and is independent of the semantic characteristic of the services. The invention disclosed in the two aforementioned documents does not cover the topic of interoperability between UPnP homed devices and session control services offered by a SIP-based network, where the syntactic issue is simply one aspect in the broader interoperability problem that requires the specification of a new UPnP device/service for the translation of SIP session control messages in UPnP methods/events and vice versa.
Mark Walker et al., “New Uses, Proposed Standards, and Emergent Device Classes for Digital Home Communications”, published on the Intel Technology Journal on Feb. 15, 2006, propose a digital home communications network for facilitating the integration, of in-home personal communication devices and extending personalized communication services to devices outside the home. In particular, they define two device classes: a Home Communications Server (HCS)—offering simple call management functions and a set of extended functionalities related to communication services, such as contact list, personalized call routing, and mailbox message management—and a Digital Communication Adaptor (DCA) that relies on the HCS and adapts legacy consumer electronics equipments such as the TV-set for use as a communication device.
The Applicant observes that the Authors of this article highlight an interest in extending UPnP-based services towards communication services, although their proposal is merely an architectural description.
The same observation applies to the architecture proposed by WO 2007/002604 and WO 2006/061682 for extending UPnP-based services towards mobile-specific services as, for example, VoIP, messaging (e.g., SMS, MMS), presence, multimedia services using SIP and SDP, conferencing applications, etc.